Expression of recombinant AccMRJP1 protein from royal jelly of Chinese honeybee in Pichia pastoris and its proliferation activity in an insect cell line

A review of fermented bee products: Sources, nutritional values, and health benefits

Bee products have garnered considerable interest due to their abundant nutritional content and versatile biological activities. The utilization of bee products as fermentation materials has shown favorable potential for increasing nutrients, altering texture, and endorsing unique tastes. This review critically examines the existing literature on fermented bee products, with a specific emphasis on the impact of fermentation on their nutritional composition and potential health benefits. The raw materials, strains, conditions, and methodologies employed in the fermentation of bee products, as well as the utilization of bee products as fermentation raw materials/excipients, are reviewed. We also present a special focus on the nutritional composition and content of bioactive substances, such as polyphenols and volatile organic compounds, in fermented bee products. Additionally, the influence of fermentation on bee product ingredients and their health benefits is summarized. Fermented bee products substantially benefit human health, with superior antioxidant, anti-inflammatory, and anti-allergic properties compared to non-fermented bee products. Finally, this article discusses the types, strains, health benefits, production processes, and market prospects of fermented bee products, which are expected to become an important part of human food culture as functional food or nutritional supplements. The aforementioned findings highlight the remarkable nutritional value and bioactive properties exhibited by fermented bee products.

Major royal jelly proteins alleviate non-alcoholic fatty liver disease in mice model by regulating disordered metabolic pathways

Nonalcoholic fatty liver disease (NAFLD), the major cause of global chronic hepatic injury, has obtained increasing attention while the current drug treatment still laid safety hazards. Major royal jelly proteins (MRJPs), the water-soluble proteins enriched in royal jelly (RJ), were applied to study its effects on improving NAFLD in the NAFLD mouse model. Herein, we demonstrated that intaking of 250-500 mg/kg/day MRJPs significantly decreased the rate of obesity, dyslipidemia, hepatic steatosis, and insulin resistance. Next, TOF to MRM ("TM") widely targeted metabolomics (untargeted metabolomics + widely targeted metabolomics) was further used to explore the potential mechanism, and we found that 500 mg/kg MRJPs alleviated lipid metabolism, oxidative stress, and inflammation mainly by regulating the metabolisms of alpha-linolenic acid, linoleic acid, arachidonic acid, and biosynthesis of unsaturated fatty acids. Moreover, by detecting multiple oxidative stress factors and inflammatory cytokines, we found that MRJPs indeed exerted antioxidant and anti-inflammatory effects. Together, we demonstrated that MRJPs could mediate the progress of NAFLD through the "multi-component-multi-target-multi-pathway" mechanism, which could be considered as an ideal functional food in alleviating NAFLD. PRACTICAL APPLICATIONS: Royal jelly (RJ) is a bee product with high nutritional value. Major royal jelly proteins (MRJPs) are water-soluble proteins in RJ. Our research showed that MRJPs significantly ameliorated NAFLD induced by a high-fat diet in mice, suggesting that MRJPs could be used as an active ingredient to help improve NAFLD, which was beneficial for the development of related functional foods and the economic value of RJ. Moreover, the metabolic pathways involved in the ameliorative effect of MRJPs were investigated, which provided new ideas for the prevention and treatment of NAFLD.

Multifunctionality and intrinsic disorder of royal jelly proteome

Royal Jelly (RJ) is a gelatinous white-yellowish fluid, possessing a sour taste and a slight phenolic smell that is secreted by the hypopharyngeal and mandibular salivary glands of the nurse honeybees, and is used in nutrition of larvae and adult queens. Similar to other substances associated with the activities of honeybees, RJ not only contains nutritive components, such as carbohydrates, proteins, peptides, lipids, vitamins, and mineral salts, but also represents a natural ingredient with cosmetic and health-promoting properties. RJ is characterized by remarkable multifunctionality, possessing numerous biological activities. Although this multifunctionality of RJ can be considered as a consequence of its complex nature, many proteins and peptides in RJ are polyfunctional entities themselves. In this article, we show that RJ proteins contain different levels of intrinsic disorder, have sites of post-translational modifications, can be found in multiple isoforms, and many of them possess disorder-based binding sites, suggesting that the conformational ensembles of the RJ proteins might undergo change as a result of their interaction with specific binding partners. All these observations suggest that the multifunctionality of proteins and peptides from RJ is determined by their structural heterogeneity and polymorphism, and serve as an illustration of the protein structure-function continuum concept.

Royal jelly-derived proteins enhance proliferation and migration of human epidermal keratinocytes in an in vitro scratch wound model

Background

Skin injury is inevitable in daily life. In recent years, with the increasing morbidity of diseases such as diabetes and metabolic disorders, chronic wounds have become a considerable challenge in clinical practice. Royal jelly, reported to have multifarious biological and physiological properties, has been used as a remedy for a variety of wounds since ancient times. However, the active components and mechanisms underlying the wound-healing properties of royal jelly are still largely unknown.

Methods

Water-soluble proteins of royal jelly were fractionated and investigated for the proliferative and migratory effects on human epidermal keratinocytes (HaCaT) in an in vitro wound healing model. The proteins present in bioactive fractions were characterised and quantified using Label-free protein quantification method. The potential functions of these proteins in biological systems were further analysed using bioinformatic tools.

Results

A protein fraction, mainly containing major royal jelly proteins 2 (MRJP2), MRJP3 and MRJP7, stimulated proliferative and migratory activities in HaCaT cells without visible cytotoxicity. It exerted the greatest effects on the growth of HaCaT cells in the first 48 h. Furthermore, when treated with this protein fraction, the closure rates of the in vitro scratch wound were significantly increased. Functional analysis indicated that MRJP2, MRJP3 and MRJP7 were associated with carbohydrate transport and metabolism.

Conclusions

We fractionated the water-soluble proteins of royal jelly and identified one fraction (Fraction 2) that induced both proliferative and migratory effects on a human epidermal keratinocyte cell line. Major royal jelly proteins (MRJP2, MRJP3 and/or MRJP7) were speculated to possess potential wound-healing bioactivity. This is the first report that royal jelly may improve wound closure via MRJP-induced cellular proliferation and migration. These proteins may be valuable lead compounds for the development of novel wound healing medications. Our findings would facilitate better understanding of the wound repair mechanisms of royal jelly.

Anti-senescence effect and molecular mechanism of the major royal jelly proteins on human embryonic lung fibroblast (HFL-I) cell line

Royal jelly (RJ) from honeybee has been widely used as a health promotion supplement. The major royal jelly proteins (MRJPs) have been identified as the functional component of RJ. However, the question of whether MRJPs have anti-senescence activity for human cells remains. Human embryonic lung fibroblast (HFL-I) cells were cultured in media containing no MRJPs (A), MRJPs at 0.1 mg/ml (B), 0.2 mg/ml (C), or 0.3 mg/ml (D), or bovine serum albumin (BSA) at 0.2 mg/ml (E). The mean population doubling levels of cells in media B, C, D, and E were increased by 12.4%, 31.2%, 24.0%, and 10.4%, respectively, compared with that in medium A. The cells in medium C also exhibited the highest relative proliferation activity, the lowest senescence, and the longest telomeres. Moreover, MRJPs up-regulated the expression of superoxide dismutase-1 (SOD1) and down-regulated the expression of mammalian target of rapamycin (MTOR), catenin beta like-1 (CTNNB1), and tumor protein p53 (TP53). Raman spectra analysis showed that there were two unique bands related to DNA synthesis materials, amide carbonyl group vibrations and aromatic hydrogens. These results suggest that MRJPs possess anti-senescence activity for the HFL-I cell line, and provide new knowledge illustrating the molecular mechanism of MRJPs as anti-senescence factors.

Architecture of the native major royal jelly protein 1 oligomer

Honeybee caste development is nutritionally regulated by royal jelly (RJ). Major royal jelly protein 1 (MRJP1), the most abundant glycoprotein among soluble royal jelly proteins, plays pivotal roles in honeybee nutrition and larvae development, and exhibits broad pharmacological activities in humans. However, its structure has long remained unknown. Herein, we identify and report a 16-molecule architecture of native MRJP1 oligomer containing four MRJP1, four apisimin, and eight unanticipated 24-methylenecholesterol molecules at 2.65 Å resolution. MRJP1 has a unique six-bladed β-propeller fold with three disulfide bonds, and it interacts with apisimin mainly by hydrophobic interaction. Every four 24-methylenecholesterol molecules are packaged by two MRJP1 and two apisimin molecules. This assembly dimerizes to form an H-shaped MRJP1₄-apisimin₄-24-methylenecholesterol₈ complex via apisimin in a conserved and pH-dependent fashion. Our findings offer a structural basis for understanding the pharmacological effects of MRJPs and 24-methylenecholesterol, and provide insights into their unique physiological roles in bees.

Transgenic silkworms secrete the recombinant glycosylated MRJP1 protein of Chinese honeybee, Apis cerana cerana

Major royal jelly protein-1 (MRJP1) is the most abundant glycoprotein of royal jelly (RJ) and is considered a potential component of functional foods. In this study, we used silkworm transgenic technology to obtain five transgenic silkworm lineages expressing the exogenous recombinant Chinese honeybee, Apis cerana cerana, protein-1 (rAccMRJP1) under the control of a fibroin light chain (Fib-L) promoter in the posterior silk glands. The protein was successfully secreted into cocoons; specifically, the highest rAccMRJP1 protein content was 0.78% of the dried cocoons. Our results confirmed that the protein band of the exogenous rAccMRJP1 protein expressed in the transgenic silkworm lineages was a glycosylated protein. Therefore, this rAccMRJP1 protein could be used as an alternative standard protein sample to measure the freshness of RJ. Moreover, we also found that the overall trend between the expression of the endogenous and exogenous genes was that the expression level of the endogenous Fib-L gene declined as the expression of the exogenous rAccMRJP1 gene increased in the transgenic silkworm lineages. Thus, by employing genome editing technology to reduce silk protein expression levels, a silkworm bioreactor expression system could be developed as a highly successful system for producing various valuable heterologous proteins, potentially broadening the applications of the silkworm.

Evaluation of the major royal jelly proteins as an alternative to fetal bovine serum in culturing human cell lines

Royal jelly (RJ) is a well-known bioactive substance. It contains large amounts of major royal jelly proteins (MRJPs), which express growth-factor-like activity in several animal and human cell lines. However, the question on whether MRJPs possess growth-factor-like activity on all types of cell cultures remains. In order to determine whether MRJPs can be used as an alternative to fetal bovine serum (FBS) in different types of human cell culture, the proliferation of the complex serum with different ratios of MRJPs/FBS (M/F) was evaluated on five cell lines: 293T, HFL-I, 231, HCT116, and Changliver using MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay. The proliferation activity of the combination of the complex M/F serum with cytokines on the test cell lines was also measured. The results demonstrated that the complex serum with M/F 6/4 possessed the highest proliferation activity similar to or in excess of FBS. However, no activity of complex medium with M/F 6/4 was observed in 231 cells, indicating a selectivity of MRJPs on cell types. Compared with the complex medium with M/F 6/4, the complex medium with M/F 6/4 together with two cytokines, epidermal growth factor (EGF) and insulin-transferrin-selenium (ITS), promoted proliferations of Changliver, 293T, HCT116, and HFL-I by 18.73%‒56.19% (P<0.01). Our findings demonstrate that MRJPs could partially replace FBS in culturing many human cell lines.

Effect of Major Royal Jelly Proteins on Spatial Memory in Aged Rats: Metabolomics Analysis in Urine

Royal jelly (RJ) produced by worker honeybees is the sole food for the queen bee throughout her life as well as the larvae of worker bees for the first 3 days after hatching. Supplementation of RJ in the diet has been shown to increase spatial memory in rodents. However, the key constituents in RJ responsible for improvement of cognitive function are unknown. Our objective was to determine if the major royal jelly proteins (MRJPs) extracted from RJ can improve the spatial memory of aged rats. The spatial memory assay using the Morris water maze test was administered once to rats after a 14-week feeding. Metabolomics analysis based on quadrupole time-of-flight mass spectrometry was conducted to examine the differences in compounds from urine. Aged male rats fed MRJPs showed improved spatial memory up to 48.5% when compared to the control male aged rats fed distilled water. The metabolite pattern of the MRJPs-fed aged rats was regressed to that of the young rats. Compounds altered by MRJPs were mapped to nicotinate and nicotinamide metabolism, cysteine taurine metabolism, and energy metabolism pathways. In summary, MRJPs may improve spatial memory and possess the potential for prevention of cognitive impairment via the cysteine and taurine metabolism and energy metabolism pathways in aged rats.

Determination of royal jelly freshness by ELISA with a highly specific anti-apalbumin 1, major royal jelly protein 1 antibody

Major royal jelly protein 1 (MRJP1), designated apalbumin 1, has been regarded as a freshness marker of royal jelly (RJ). A MRJP1-specific peptide (IKEALPHVPIFD) identified by bioinformatics analysis of homologous members of the major royal protein family was synthesized and used to raise polyclonal anti-MRJP1 antibody (anti-SP-MRJP1 antibody). Western blot analysis showed that anti-SP-MRJP1 antibody only reacted with MRJP1 in RJ. In contrast, the previously reported antibody against recombinant MRJP1 (anti-R-MRJP1 antibody) reacted with other members of MRJP family in RJ. Enzyme-linked immunosorbent assay (ELISA) using anti-SP-MRJP1 antibody demonstrated that MRJP1 content in RJ stored at 40 °C significantly degraded by 37.3%, 55.9%, 58.0%, 60.6%, 65.7%, 72.7%, and 73.1% at 7, 14, 21, 28, 35, 42, and 49 d, respectively, when compared with MRJP1 content in fresh RJ (0 d). Optical density analysis of MRJP bands from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles demonstrated that the degradation of MRJP1, MRJP2, MRJP3, and MRJP5 in RJ was strongly and positively correlated with the period of storage (P<0.0001). Our results indicated anti-SP-MRJP1 antibody was highly specific for MRJP1, and ELISA using the antibody is a sensitive and easy-to-use method to determine the freshness and authenticity of RJ.

Heat Resistant Characteristics of Major Royal Jelly Protein 1 (MRJP1) Oligomer

Soluble royal jelly protein is a candidate factor responsible for mammiferous cell proliferation. Major royal jelly protein 1 (MRJP1), which consists of oligomeric and monomeric forms, is an abundant proliferative protein in royal jelly. We previously reported that MRJP1 oligomer has biochemical heat resistance. Therefore, in the present study, we investigated the effects of several heat treatments (56, 65 and 96°C) on the proliferative activity of MRJP1 oligomer. Heat resistance studies showed that the oligomer molecular forms were slightly maintained until 56℃, but the molecular forms were converted to macromolecular heat-aggregated MRJP1 oligomer at 65℃ and 96℃. But, the growth activity of MRJP1 oligomer treated with 96°C was slightly attenuated when compared to unheated MRJP1 oligomer. On the other hand, the cell proliferation activity was preserved until 96℃ by the cell culture analysis of Jurkat cells. In contrast, those of IEC-6 cells were not preserved even at 56°C. The present observations suggest that the bioactive heat-resistance properties were different by the origin of the cells. The cell proliferation analysis showed that MRJP1 oligomer, but not MRJP2 and MRJP3, significantly increased cell numbers, suggesting that MRJP1 oligomer is the predominant proliferation factor for mammiferous cells.

Origin and function of the major royal jelly proteins of the honeybee (Apis mellifera) as members of the yellow gene family

In the honeybee, Apis mellifera, the queen larvae are fed with a diet exclusively composed of royal jelly (RJ), a secretion of the hypopharyngeal gland of young worker bees that nurse the brood. Up to 15% of RJ is composed of proteins, the nine most abundant of which have been termed major royal jelly proteins (MRJPs). Although it is widely accepted that RJ somehow determines the fate of a female larva and in spite of considerable research efforts, there are surprisingly few studies that address the biochemical characterisation and functions of these MRJPs. Here we review the research on MRJPs not only in honeybees but in hymenopteran insects in general and provide metadata analyses on genome organisation of mrjp genes, corroborating previous reports that MRJPs have important functions for insect development and not just a nutritional value for developing honeybee larvae.

Fast determination of adenosine 5'-triphosphate (ATP) and its catabolites in royal jelly using ultraperformance liquid chromatography

To obtain insight into the metabolic regulation of adenosine 5'-triphosphate (ATP) in royal jelly and to determine whether ATP and its catabolites can be used as objective parameters to evaluate the freshness and quality of royal jelly (RJ), a rapid ultraperformance liquid chromatography (UPLC) method has been developed for feasible separation and quantitation of ATP and its catabolites in RJ, namely, adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP), inosine monophosphate (IMP), inosine (HxR), and hypoxanthine (Hx). The analytes in the sample were extracted using 5% precooled perchloric acid. Chromatographic separation was performed on a Waters Acquity UPLC system with a Waters BEH Shield RP18 column and gradient elution based on a mixture of two solvents: solvent A, 50 mM phosphate buffer (pH 6.5); and solvent B, acetonitrile. The recoveries were in the range of 86.0-102.3% with RSD of no more than 3.6%. The correlation coefficients of six analytes were high (r(2) ≥ 0.9988) and within the test ranges. The limits of detection and quantification for the investigated compounds were lower, at 0.36-0.68 and 1.22-2.30 mg/kg, respectively. The overall intra- and interday RSDs were no more than 1.8%. The developed method was successfully applied to the analysis of the analytes in samples. The results showed that ATP in RJ sequentially degrades to ADP, AMP, IMP, HxR, and Hx during storage.